Reaching a ceiling in test administration is not the same kind of ceiling as the ceiling of the test. A test administration ceiling is a discontinue rule. In this case, it means he did not get four out of five consecutive items wrong, prior to running out of items to do. This does not mean he got every item correct all the way up to the last four or five items. When you see this happen, it suggests that the scaled score may be a low estimate of ability, as the test may not have had sufficient range to capture all of his skill.
